In Situ Infrared Spectroscopy of Glyoxylic Acid Adsorption and Photocatalysis on TiO₂ in Aqueous Solution

Abstract

In situ internal reflectance infrared spectroscopy has been used to monitor the adsorption from aqueous solution and the photocatalysis of glyoxylic acid (HCO−COOH) on a thin TiO 2 particle film deposited on a ZnSe single reflection prism. Glyoxylic acid was found to adsorb to TiO 2 as the glyoxylate ion with bidentate coordination via the hydroxyls of the carboxylic acid group and of the hydrated aldehyde group. Near-UV irradiation of the adsorbed glyoxylate resulted in its conversion to adsorbed oxalate on the TiO 2 . A significant absorption at 878 cm -1, which appeared under near-UV irradiation of the photocatalytic system, may be due to changes in the TiO 2 surface structure or formation of surface peroxo species.